Mishkat al-Masabih 4 Prayer كتاب الصلاة 619

وَعَنِ ابْنِ عَبَّاسٍ قَالَ: كَانَتْ قِرَاءَةُ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَلَى قَدْرِ مَا يَسْمَعُهُ مَنْ فِي الْحُجْرَةِ وَهُوَ فِي الْبَيْتِ. رَوَاهُ أَبُو دَاوُد

Ibn ‘Abbas said the Prophet’s recitation was loud enough for one who was in the inner chamber to hear it when he was in the house. Abu Dawud transmitted it.